Methane at the NW of Weddell Sea, Antarctica

Abstract

The presence of gaseous hydrocarbons (from methane to n-pentane) in the seabed sediments and the bubbling of methane may suggest the presence of gas accumulations in the substrate of the NW Weddell Sea, Antarctica. The release of methane from the frozen ocean substrate adjacent to Seymour Island would be linked to climate instability during Late Cenozoic, when vast areas of the Antarctic continental shelf were flooded during the marine transgression that occurred . 18,000 years ago, after the Last Glacial Maximum (LGM). As the ice melted, the sea again occupied the regions which it had abandoned. As the transgression was relatively rapid, the sub-air relief was not destroyed but was submerged and the ground had frozen (permafrost) along with it. Thus, the heat flow from the sea to the marine substrate, now flooded, would have destabilized frozen gas accumulations, which were originally formed into terrestrial permafrost during the LGM, similarly to what would have happened in the Arctic.

The morphology of pockmarks on the north-east Antarctic Peninsula continental shelf

“…Although the presence of gas hydrates has not been confirmed on the north-east Antarctic Peninsula margin, it has been inferred previously from the detection of methane within sea-floor sediments adjacent to Seymour Island (Fig. 1; del Valle et al 2017). Gas-hydrate destabilization on glaciated margins has been linked to depressurization by the removal of grounded ice and the increase in ocean temperature that accompanied the last deglaciation (Solheim & Elverhøi 1993, Winsborrow et al 2016, Böttner et al 2019).…”

Gas Hydrates in Antarctica

“…Only in the last years, the extraordinary rapid climate warming, which is occurring in the northern tip of the Antarctic Peninsula [49,50], caused the reduction of land ice along West Antarctica and the ice shelves destruction in the surrounding seas (i.e., "in [51,52]"). In north-western of Weddell Sea, [53] detected the presence of gaseous hydrocarbons (from methane to n-pentane) in the seabed sediments and the bubbling of methane suggesting the presence of gas accumulations in the substrate of the NW Weddell Sea. They observed a release of methane from the frozen ocean substrate adjacent to Seymour Island, linked to climate instability during Late Cenozoic, when vast areas of the Antarctic continental shelf were flooded during the marine transgression that occurred .…”

“…18,000 years ago, after the Last Glacial Maximum. The heat flow from the sea to the marine substrate, now flooded, would have destabilized frozen gas accumulations, which were originally formed into terrestrial permafrost during the Last Glacial Maximum, similarly to what would have happened in the Arctic [53].…”